Metal melting furnace



June 23, 1959 K. A. LANG Em 2,892,005

,METAL MELTING FURNACE 2 Sheets-Sheet A1 Filed Nov. 14, 1955 ATTURNE YS.

United States *,Patent O METAL MELTING FURNACE Karl A. Lang, Glenview,andCary H. Stevenson, Chicago,

vIll., assguors to Lindberg Engineering Company, Chicago, Ill., acorporation of Illinois 1 This 'invention yrelates to -rnetal meltingyfurnaces' and more particularly to a combined fuel tired 'and electricinduction furnace.

vIt has been the common practice for many years to melt .metal in fueltired furnaces, such as reverberatory furnaces. In the use of suchfurnaces, it has been customary to charge the furnace with a full chargeand when the metal is melted to tap the hearth and withdraw the moltencharge. Furnaces of this type are therefore not adaptable to continuousservice where small portions of the complete charge are to be withdrawnperiodically or where continuous discharge is desired.

Reverberatory furnaces have in some cases been provided with externalholding chambers from which molten metal can be ladled or pumped in aneffort to meet the demands of continuous service. The metal tends tochill in such holding chambers, however, with the result that metal inthe mainhearth must be overheated to maintain the metal in the holdingchamber at the proper temperature.

Itv is'accordingly one of the objects of the present nvention to providea metal melting furnace in which an external holding chamber is providedin conjunction with a fuel fired furnace and the metal in the holdingchamber is maintained heated by electric induction.

Another object is to provide a metal melting furnace, including twoholding chambers one of which may serve as a settling or fluxing chamberand the other as either a discharge or charging chamber with the metalin both holding chambers heated by electric induction.

According to one feature of the invention, the rst holding chamber maybe heated by passing hot gases from the reverberatory furnace through ahollow roof thereon.

The above and other objects and features of the invention will be morereadily apparent from the following description when read in connectionwith the accompanying drawings, in which:

Figure 1 is a diagrammatic plan view of a metal melting furnaceembodying the invention;

Figure 2 is a transverse section through the furnace of Figure l on thebroken line 2 2;

Figure 3 is a diagrammatic plan View of an alternative form of furnaceembodying the invention;

Figure 4 is a section on the line 4--4 of Figure 3; and

Figure 5 is a section on the 'broken line 5 5 of Figure 3.

The `furnace of Figures l and 2 comprises a main reverberatory sectionincluding a chamber formed of refractory material, or the like, having adoor opening 11 at one end which is normally closed by a cover 12. Thechamber 10 may be provided with a lateral charging extension 13 throughwhich metal to be melted may -be inserted therein without requiringopening of the furnace chamber and is adapted to hold molten metal inits lower part to substantially the level of line 14 in Figure 2.

2,892,005 .s Patented Junel'l23`,

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The main reverberatory chamberll is heated in the usual mannerbyburners` 15 extendingrinto the chamber beneath the closed -arched roof16 thereof and adapted to burn any suitable fuel, suchy as gas or thelike. Thecornbustio'n gases llow across the roof of the furnace and maybe discharged through a ue 17, as seen in Figure l. The hot combustion'gases will heat the chamber and will melt metal 'in the lowervpart'thereof and maintain the metal molten."

vA holding chamber 18 is mounted in laterallyspaced relation tov themain reverberatory unit and communicates therewith through' submergedinclined channels 19. As shown, two such channels 19 are provided foruse with single phase heating current, although if desii-ed three ormore channels could be provided for use with polyphase current.V Thechannels arethreaded by a primary unit including a magnetic core 21extending between the channels and around one of them and which maycarry a primary winding to' be energized by alternating current toyproduce a'tiine varying fluxcutting the channels. VAs is-well understoodin the art,this

will induce a flow of heating cunrent inthe' channels :through theclosed loop created by the channels, the main reverberatory hearth andthe holding chamber.

In use of the furnace, metal is charged in the main reverberatory hearthand is melted therein by the heat produced by the fuel burners 415. Themolten metal will flow through the channelsl 19 into thevholding'chamber 18 and when the primary 21 is energized heating currentwill -be energized in the-metal in the channels and heating chamber tomaintain it at the desired temperature. Thus, with this construction themetal in the mainreverberatory hearth can be Vmaintained at the correcttemperature' and molten metal can `be ladled, pumped, or poured from theholding chamber. 18 intermittently'or continuously, as desired. Themetalfinthe holding chamber will be maintained at the correcttemperature at all times -by the heating current induced in the channels19 without creating or requiring any excessive heating of metal in anypart of the unit. It will also be noted that partial charges of metalcan be added to the reverberatory hearth from time to time withoutcreating excessive cooling in the holding chamber so that the furnace iscapable of substantially continuous operation.

The construction shown in Figures 3, 4 and 5 comprises a mainreverberatory unit 22 having a closed arched roof 23 and providing ahearth in its lower portion to hold a molten charge. The furnace may becharged through an opening 24 normally closed by a door 25 and may, ifdesired, be provided with a tapping opening 26. The reverberatorychamber is heated by fuel burners 27 extending into the upper portionthereof and fired by gas or other fuel, as desired.

A rst holding chamber 28 displaced horizontally from the reverberatoryhearth communicates therewith through a submerged port 29 to receivemolten metal from the reverberatory hearth. The holding chamber 28 maybe provided with an arched roof 31 which is hollow to provide fluepassages 32, as best seen in Figures 4 and 5. The passages 32communicate at one end with the reverberatory chamber and at their otherends are connected to a ue 33 so that hot gases from the reverberatorychamber in owing through the passages 32 will heat the roof 31 of thefirst holding chamber to maintain the metal molten therein.

The first holding chamber communicates with a second holding chamber 34spaced horizontally from both the first holding chamber and the hearth.The second holding chamber 34 communicates with the rst holding chamber28 through submerged inclined channels 35 there being two such channelshorizontally spaced, as seen in Figure 3. The channels 35 are threadedby a primary unit 36, including a closed magnetic core carrying aWinding which may be energized by alternating current to induce a flowof heating current in the molten metal in the channels and through themetal in the two holding chambers. In this way, the metal in the firstholding chamber is additionally heated and the metal in the sec ondholding chamber 34 may be maintained at the correct temperature withoutinterfering with operation of the main reverberatory unit.

In using this furnace the main reverberatory hearth may be charged andmetal may be withdrawn intermittently or continuously from the secondholding chamber 34. If desired, the first holding chamber 28 could betapped through a tap 37. In either case, the metal throughout thecomplete furnace installation will be mairr tained at the correcttemperature without requiring any overheating.

For starting up the furnace after shut down to assist in melting theinitial charge, the first holding chamber 28 may be provided with fuelburners 38 in the upper part thereof. Normally such burners will not berequired for running, but may be helpful in starting the furnace whenthe metal therein is in solid condition.

While two embodiments of the invention have been shown and describedherein, it will be understood that they are illustrative only and not tobe taken as a definition of the scope of the invention, reference beinghad for this purpose to the appended claims.

What is claimed is:

1. A metal melting furnace comprising a main hearth, fuel fired meansIfor heating metal in the main hearth, a first holding chamber spacedfrom the main hearth and communicating therewith to receive molten metaltherefrom, a second holding chamber spaced from the first holdingchamber, submerged channels connecting the first and second holdingchambers, and a primary threading the channels to induce heating currentin the metal therein.

2. A metal melting furnace comprising a main hearth,

fuel fired means for heating metal in the main hearth, a first holdingchamber spaced from the main hearth and communicating therewith toreceive molten metal therefrom, a roof over the first holding chamber,means to heat the roof thereby to heat metal in the first holdingchamber, a second holding chamber spaced from the first holding chamber,submerged channels connecting the first and second holding chambers, anda primary threading the channels to induce heating current in the metaltherein.

3. A metal melting furnace comprising a reverberatory unit including ahearth, a roof over the hearth, and fuel burners beneath the roof toheat metal in the hearth, a first holding chamber spaced from thereverberatory unit and communicating with the hearth to receive moltenmetal therefrom, a second holding chamber spaced from the first holdingchamber, submerged channels connecting the first and second holdingchambers, and a primary threading the channels to induce heating currentin the metal therein.

4. A metal melting furnace comprising a reverberatory unit including ahearth, a roof over the hearth, and fuel burners beneath the roof toheat metal in the hearth, a first holding chamber spaced from thereverberatory unit and communicating with the hearth to receive moltenmetal therefrom, a hollow roof over the first holding chambercommunicating with the reverberatory unit to receive heated gastherefrom to heat the metal in the first holding chamber, a secondholding chamber spaced from the first holding chamber, submergedchannels connecting the first and second holding chambers, and a primarythreading the channels to induce heating current n the metal therein.

References Cited in the file of this patent UNITED STATES PATENTS1,694,536 Foley Dec. 11, 1928 1,851,575 Greene Mar. 29, 1932 2,067,110Wyatt Jan. 5, 1937 2,106,456 Howard et al. Jan. 25, 1938

